1. Field of the Invention
Embodiments of the invention relate to a semiconductor device manufacturing apparatus and a method for fabricating a semiconductor device. More particularly, embodiments of the invention relate to an apparatus adapted to bake a wafer and a related method.
This application claims priority to Korean Patent Application 2005-57241, filed on Jun. 29, 2005, the subject matter of which is hereby incorporated by reference in its entirety.
2. Description of the Related Art
Semiconductor devices are manufactured through a complex series of fabrication processes such as cleaning, deposition, photolithography, etching, and ion implantation processes. A photolithography process adapted to form patterns on a wafer is critical to the formation of highly integrated semiconductor devices.
In general, systems adapted to perform photolithography comprise a coating apparatus, an exposure apparatus, a developing apparatus, and a plurality of baking apparatuses. The exposure apparatus performs an exposure process in which the exposure apparatus irradiates light onto the photoresist layer formed on the wafer. By irradiating light onto the photoresist layer, the exposure apparatus transforms properties of various regions of the photoresist layer, and thus forms “altered photoresist regions” in the photoresist layer. Deep ultra-violet light has recently been replacing the conventional i-line type light as the light used by the exposure process as design rules for contemporary semiconductor devices have been scaled down.
When deep ultraviolet light is used in the exposure process, the post-exposure baking process is indispensable in the fabrication of the semiconductor device. By heating a wafer on which the exposure process was performed, the post-exposure baking process further transforms properties of regions of the photoresist layer by amplifying the acid generated in the photoresist layer. The amount that the acid in the photoresist layer is amplified, and thus, the respective dimensions of the altered photoresist regions after the post-exposure baking process is performed, depends upon the temperature at which the wafer is heated during the post-exposure baking process. When the wafer is heated at an insufficient temperature (i.e., a temperature that is too low), the acid amplification is suppressed and only narrow altered photoresist regions are formed.
While light is irradiated precisely onto a central region of the wafer during photolithography, light may also be broadly irradiated onto edge regions of the wafer for various reasons. For example, a wafer seated on a vacuum wafer chuck may be slightly bent, and the resulting, slightly curved surface may allow light to be irradiated on edge regions of the wafer.
In an attempt to form uniform photoresist patterns over an entire wafer, conventional post-exposure baking apparatuses have been adapted to apply heat uniformly to an entire wafer. However, during post-exposure baking process, some wider, altered photoresist regions may be formed on an edge region of a wafer due to the incident irradiation phenomenon noted above. Thus, after a development process, some portions of the remaining photoresist pattern may be more narrow than desired. Such overly narrow photoresist pattern portions may fail to adhere to wafer, but instead may break off and become loose potentially contaminating particles on the wafer.